OpenAtlas

Performance improvements are getting quite tricky with a complex model and much data.
The last changes got us around 20% overall speed gain. It could be better but waiting for new map implementations for next round.

- added transactions
- reduced system and user logging
- refactored insert entity/link to also accept ids instead of objects
- refactored insert entity/link to return ids instead of objects

tried (but no significant performance gain)

- turning off link checker
- views
- database connection without Zend Framework
- PDO with persistent connection
- pg_bouncer